Slab saws are commonly used for generating cuts in pavement, stone and other hard surfaces typically found in outside environments. A typical slab saw includes a frame supported by wheels, a power unit for driving the saw, such as a gas or diesel motor, and a rotary blade. Pavement cuts formed by a slab saw may be used for a variety of purposes, including forming a narrow trench for installation of cables. In one application, a slab saw may be used to cut through an overlying pavement layer into the sub-grade material. Conventionally, this has been carried out via a wet-cutting process, involving directing a stream of water onto the saw blade for cooling and to wash away the dust generated by the cutting action. Wet-cutting of this type typically generates a relatively large volume of mud, which requires cleaning and disposal. As well, wet-cutting typically deposits a layer of mud on the walls of the cut. In certain applications, it is desirable to provide a clean cut, for example where the resulting cut is used for installation of cables and the like. For this application, the deposited mud layer must be cleaned from the inside of the cut, which requires considerable effort and water. It is therefore desirable to provide a dry cutting method, which leaves a relatively clean cut while also permitting easier removal and disposal of the dust resulting from the cutting operation. However, a challenge in providing a dry cutting method is to evacuate the dust generated by the blade in an easy and convenient manner.
Circular saws for carpentry use typically include a full or partial shroud for trapping of dust. The shroud may communicate with a vacuum source, for disposal of the dust. An example of a carpenter's saw of this type is shown in U.S. Pat. No. 5,327,649, to Sklower. A dust shroud for a portable circular saw is also described in U.S. Pat. No. 4,241,505, to Bodycomb, Jr., et al., which describes a portable circular saw having a two-part dust shroud consisting of upper and lower housings, joined together by an external attachment link. The housings are spaced apart, to permit a workpiece to be received between the housings during cutting
Dust collection shrouds for circular saws are also disclosed in U.S. Pat. No. 4,255,995 to Connor, U.S. Pat. No. 4,063,478 to Stuy and U.S. Pat. No. 4,253,362 to Olson.
Circular saws for carpentry, while often including a shroud for collecting dust, differ from slab saws for pavement cutting. Slab saws present different challenges from carpentry saws for preventing dust dispersal. Hence, there is a need for a convenient system for containing and removing dust during operation of a slab saw.